Define ionisation energy

Ionisation energy ( IE ) is the energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous positive ions. Units: kJ mol -1 .

Define first ionisation energy

First ionisation energy ( IE 1 ) is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions: X (g) → X + (g) + e -

Write the equation representing the second ionisation energy of calcium.

Ca + (g) → Ca 2+ (g) + e - The second ionisation energy ( IE 2 ) removes one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

The four factors that affect the size of the first ionisation energy are: nuclear charge, distance of outer electrons from the nucleus, shielding by inner electrons, and ..........

The four factors that affect the size of the first ionisation energy are: nuclear charge, distance of outer electrons from the nucleus, shielding by inner electrons, and spin-pair repulsion .

Why does increasing shielding by inner electrons lower the ionisation energy?

Shielding reduces the attractive force felt by the outer electron from the nucleus. The inner electrons partially cancel the nuclear charge, making it easier to remove the outer electron and lowering the ionisation energy.

True or False? Successive ionisation energies of an element always increase steadily with no large jumps.

False. Large jumps in successive ionisation energies occur when an electron is removed from a shell closer to the nucleus. These jumps reveal the number of electrons in each shell.

How does spin-pair repulsion affect the ionisation energy of a paired electron?

Spin-pair repulsion between two electrons sharing an orbital partially offsets the nuclear attraction. This makes the paired electron slightly easier to remove, lowering its ionisation energy compared to an unpaired electron in the same subshell.

Each atomic orbital can hold a maximum of .......... electrons, which must have opposite spins.

Each atomic orbital can hold a maximum of two electrons, which must have opposite spins. This is a consequence of the Pauli Exclusion Principle.

True or False? Ionisation energies are measured under standard conditions of 298 K and 101 kPa.

True. The RN states: "Ionisation energies are measured under standard conditions which are 298 K and 101 kPa."

What information about an element can be deduced from its successive ionisation energy data?

Successive ionisation energy data reveals the electronic configuration: the number of electrons in the outer shell, the shell structure, and the group of the element in the Periodic Table.

What is a successive ionisation energy ?

A successive ionisation energy is the energy required to remove each subsequent electron from an increasingly positive ion. Values increase with each successive removal.

A large jump between the 2nd and 3rd successive ionisation energies indicates that the element is in group .......... of the Periodic Table.

A large jump between the 2nd and 3rd successive ionisation energies indicates that the element is in group 2 of the Periodic Table. The jump shows that the 3rd electron is in a shell closer to the nucleus, so two electrons are in the outer shell.

True or False? Successive ionisation energies show that inner-shell electrons require less energy to remove than outer-shell electrons.

False. Inner-shell electrons are closer to the nucleus and experience greater nuclear attraction with less shielding, so they require considerably more energy to remove.

For sodium (Na), between which two successive ionisation energies is the largest jump, and what does this indicate?

The largest jump in sodium is between IE 1 and IE 2 . This indicates that sodium has only one electron in its outer shell, confirming it belongs to group 1 (electron configuration: 1s 2 2s 2 2p 6 3s 1 ).

Why is there a smaller jump between successive ionisation energies when moving between subshells within the same principal quantum shell?

When moving between subshells in the same shell, the change in distance from the nucleus and shielding is small. This produces a modest increase in ionisation energy rather than the large jump seen when changing principal quantum shells.

An element has IE 1 = 899, IE 2 = 1757, IE 3 = 14850 kJ mol -1 . The element is in group ..........

An element has IE 1 = 899, IE 2 = 1757, IE 3 = 14850 kJ mol -1 . The element is in group 2 . The large jump between IE 2 and IE 3 shows the 3rd electron is in an inner shell, so there are 2 outer-shell electrons.

True or False? For calcium, the first electron removed is harder to remove than the second because of spin-pair repulsion.

False. The first electron removed from calcium benefits from spin-pair repulsion in the 4s orbital, making it easier to remove than the second. IE 1 < IE 2 for calcium.

What is an atomic orbital ?

An atomic orbital is a region of space around the nucleus that can hold a maximum of two electrons with opposite spins. Electrons exist at specific energy levels within orbitals.

What are the shapes of s orbitals and p orbitals?

s orbitals are spherical. p orbitals have a dumbbell shape with two lobes oriented along the x, y or z axis. Each shell (from n = 2) has three p orbitals at right angles to each other.

The s subshell holds a maximum of 2 electrons, the p subshell 6, the d subshell 10, and the f subshell ..........

The s subshell holds a maximum of 2 electrons, the p subshell 6, the d subshell 10, and the f subshell 14 . Each orbital holds 2 electrons: s has 1 orbital, p has 3, d has 5 and f has 7.

True or False? The size of s orbitals increases with increasing principal quantum number.

True. Higher principal quantum shells are further from the nucleus, so the s orbital in the third shell ( n = 3) is larger than the s orbital in the first shell ( n = 1).

What is Hund's Rule ?

Hund's Rule states that electrons occupy separate orbitals within the same subshell before pairing up. Single electrons fill orbitals with parallel spin first to minimise spin-pair repulsion.

What does the Pauli Exclusion Principle state about electrons in an orbital?

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers. Consequently, each orbital holds at most two electrons and they must have opposite spins.

Electrons occupy separate orbitals in the same subshell first to minimise ..........

Electrons occupy separate orbitals in the same subshell first to minimise spin-pair repulsion . This is the basis of Hund's Rule.

True or False? The first quantum shell ( n = 1) contains both s and p orbitals.

False. The first shell ( n = 1) contains only one s orbital. p orbitals are present from the second shell ( n = 2) onwards.

Why do electrons pair up in an orbital rather than always occupying the next empty orbital?

The energy required to jump to a higher empty orbital is greater than the repulsion energy between two electrons in the same orbital. Electrons therefore pair up in lower-energy orbitals once all orbitals in a subshell are singly occupied.

What determines which block (s, p, d or f) an element belongs to in the Periodic Table?

An element's block is determined by the subshell containing its outermost electron . If the highest-energy electron is in an s orbital, the element is in the s block; p in the p block, and so on.

What is a shorthand electron configuration ?

A shorthand electron configuration uses the symbol of the nearest preceding noble gas in square brackets to represent its electron arrangement, followed by the configuration of the remaining electrons. Example: potassium is [Ar] 4s 1 .

Subshells increase in energy in the order: s < p < d < f, with one exception: the .......... orbital is higher in energy than the 4s orbital.

Subshells increase in energy in the order: s < p < d < f, with one exception: the 3d orbital is higher in energy than the 4s orbital. This means the 4s orbital is filled before the 3d.

True or False? Transition metals lose electrons from the 3d subshell before the 4s subshell when forming positive ions.

False. Transition metals lose electrons from the 4s subshell first when forming positive ions, even though the 4s is filled before the 3d.

Write the full electron configuration of calcium (atomic number 20).

Calcium: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 The shorthand version is [Ar] 4s 2 .

Chromium has an electron configuration of [Ar] 3d 5 4s 1 rather than [Ar] 3d 4 4s 2 because the .......... configuration is energetically more stable.

Chromium has an electron configuration of [Ar] 3d 5 4s 1 rather than [Ar] 3d 4 4s 2 because the half-filled d subshell configuration is energetically more stable.

True or False? Elements in the same group of the Periodic Table have the same number of outer-shell electrons.

True. All elements in the same group have the same number of electrons in their outermost shell. This gives them similar chemical properties.

Why do noble gases have very high ionisation energies and rarely react?

Noble gases have full subshells in their outermost shell, giving a very stable electronic arrangement. This makes it very difficult to remove an electron, so they rarely participate in chemical reactions.

What is the electron configuration of Ca 2+ , and which neutral atom has the same configuration?

Ca 2+ has the configuration 1s 2 2s 2 2p 6 3s 2 3p 6 . This is identical to the configuration of argon .

International A Level (IAL)ChemistryEdexcelFlashcards1. Structure, Bonding & Introduction to Organic ChemistryElectrons & Ions

Electrons & Ions (Edexcel International A Level (IAL) Chemistry): Flashcards

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Define ionisation energy

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Define ionisation energy
Ionisation energy (IE) is the energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous positive ions. Units: kJ mol^-1.
Define first ionisation energy
First ionisation energy (IE₁) is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions:
X (g) → X⁺ (g) + e^-
Write the equation representing the second ionisation energy of calcium.
Ca⁺ (g) → Ca²⁺ (g) + e^-
The second ionisation energy (IE₂) removes one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
The four factors that affect the size of the first ionisation energy are: nuclear charge, distance of outer electrons from the nucleus, shielding by inner electrons, and ..........
The four factors that affect the size of the first ionisation energy are: nuclear charge, distance of outer electrons from the nucleus, shielding by inner electrons, and spin-pair repulsion.
Why does increasing shielding by inner electrons lower the ionisation energy?
Shielding reduces the attractive force felt by the outer electron from the nucleus. The inner electrons partially cancel the nuclear charge, making it easier to remove the outer electron and lowering the ionisation energy.
True or False?
Successive ionisation energies of an element always increase steadily with no large jumps.
False.
Large jumps in successive ionisation energies occur when an electron is removed from a shell closer to the nucleus. These jumps reveal the number of electrons in each shell.
How does spin-pair repulsion affect the ionisation energy of a paired electron?
Spin-pair repulsion between two electrons sharing an orbital partially offsets the nuclear attraction. This makes the paired electron slightly easier to remove, lowering its ionisation energy compared to an unpaired electron in the same subshell.
Each atomic orbital can hold a maximum of .......... electrons, which must have opposite spins.
Each atomic orbital can hold a maximum of two electrons, which must have opposite spins.
This is a consequence of the Pauli Exclusion Principle.
True or False?
Ionisation energies are measured under standard conditions of 298 K and 101 kPa.
True.
The RN states: "Ionisation energies are measured under standard conditions which are 298 K and 101 kPa."
What information about an element can be deduced from its successive ionisation energy data?
Successive ionisation energy data reveals the electronic configuration: the number of electrons in the outer shell, the shell structure, and the group of the element in the Periodic Table.
What is a successive ionisation energy?
A successive ionisation energy is the energy required to remove each subsequent electron from an increasingly positive ion. Values increase with each successive removal.
A large jump between the 2nd and 3rd successive ionisation energies indicates that the element is in group .......... of the Periodic Table.
A large jump between the 2nd and 3rd successive ionisation energies indicates that the element is in group 2 of the Periodic Table.
The jump shows that the 3rd electron is in a shell closer to the nucleus, so two electrons are in the outer shell.
True or False?
Successive ionisation energies show that inner-shell electrons require less energy to remove than outer-shell electrons.
False.
Inner-shell electrons are closer to the nucleus and experience greater nuclear attraction with less shielding, so they require considerably more energy to remove.
For sodium (Na), between which two successive ionisation energies is the largest jump, and what does this indicate?
The largest jump in sodium is between IE₁ and IE₂. This indicates that sodium has only one electron in its outer shell, confirming it belongs to group 1 (electron configuration: 1s² 2s² 2p⁶ 3s¹).
Why is there a smaller jump between successive ionisation energies when moving between subshells within the same principal quantum shell?
When moving between subshells in the same shell, the change in distance from the nucleus and shielding is small. This produces a modest increase in ionisation energy rather than the large jump seen when changing principal quantum shells.
An element has IE₁ = 899, IE₂ = 1757, IE₃ = 14850 kJ mol^-1. The element is in group ..........
An element has IE₁ = 899, IE₂ = 1757, IE₃ = 14850 kJ mol^-1. The element is in group 2.
The large jump between IE₂ and IE₃ shows the 3rd electron is in an inner shell, so there are 2 outer-shell electrons.
True or False?
For calcium, the first electron removed is harder to remove than the second because of spin-pair repulsion.
False.
The first electron removed from calcium benefits from spin-pair repulsion in the 4s orbital, making it easier to remove than the second. IE₁ < IE₂ for calcium.
What is an atomic orbital?
An atomic orbital is a region of space around the nucleus that can hold a maximum of two electrons with opposite spins. Electrons exist at specific energy levels within orbitals.
What are the shapes of s orbitals and p orbitals?
s orbitals are spherical. p orbitals have a dumbbell shape with two lobes oriented along the x, y or z axis. Each shell (from n = 2) has three p orbitals at right angles to each other.
The s subshell holds a maximum of 2 electrons, the p subshell 6, the d subshell 10, and the f subshell ..........
The s subshell holds a maximum of 2 electrons, the p subshell 6, the d subshell 10, and the f subshell 14.
Each orbital holds 2 electrons: s has 1 orbital, p has 3, d has 5 and f has 7.
True or False?
The size of s orbitals increases with increasing principal quantum number.
True.
Higher principal quantum shells are further from the nucleus, so the s orbital in the third shell (n = 3) is larger than the s orbital in the first shell (n = 1).
What is Hund's Rule?
Hund's Rule states that electrons occupy separate orbitals within the same subshell before pairing up. Single electrons fill orbitals with parallel spin first to minimise spin-pair repulsion.
What does the Pauli Exclusion Principle state about electrons in an orbital?
The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers. Consequently, each orbital holds at most two electrons and they must have opposite spins.
Electrons occupy separate orbitals in the same subshell first to minimise ..........
Electrons occupy separate orbitals in the same subshell first to minimise spin-pair repulsion.
This is the basis of Hund's Rule.
True or False?
The first quantum shell (n = 1) contains both s and p orbitals.
False.
The first shell (n = 1) contains only one s orbital. p orbitals are present from the second shell (n = 2) onwards.
Why do electrons pair up in an orbital rather than always occupying the next empty orbital?
The energy required to jump to a higher empty orbital is greater than the repulsion energy between two electrons in the same orbital. Electrons therefore pair up in lower-energy orbitals once all orbitals in a subshell are singly occupied.
What determines which block (s, p, d or f) an element belongs to in the Periodic Table?
An element's block is determined by the subshell containing its outermost electron. If the highest-energy electron is in an s orbital, the element is in the s block; p in the p block, and so on.
What is a shorthand electron configuration?
A shorthand electron configuration uses the symbol of the nearest preceding noble gas in square brackets to represent its electron arrangement, followed by the configuration of the remaining electrons.
Example: potassium is [Ar] 4s¹.
Subshells increase in energy in the order: s < p < d < f, with one exception: the .......... orbital is higher in energy than the 4s orbital.
Subshells increase in energy in the order: s < p < d < f, with one exception: the 3d orbital is higher in energy than the 4s orbital.
This means the 4s orbital is filled before the 3d.
True or False?
Transition metals lose electrons from the 3d subshell before the 4s subshell when forming positive ions.
False.
Transition metals lose electrons from the 4s subshell first when forming positive ions, even though the 4s is filled before the 3d.
Write the full electron configuration of calcium (atomic number 20).
Calcium: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
The shorthand version is [Ar] 4s².
Chromium has an electron configuration of [Ar] 3d⁵ 4s¹ rather than [Ar] 3d⁴ 4s² because the .......... configuration is energetically more stable.
Chromium has an electron configuration of [Ar] 3d⁵ 4s¹ rather than [Ar] 3d⁴ 4s² because the half-filled d subshell configuration is energetically more stable.
True or False?
Elements in the same group of the Periodic Table have the same number of outer-shell electrons.
True.
All elements in the same group have the same number of electrons in their outermost shell. This gives them similar chemical properties.
Why do noble gases have very high ionisation energies and rarely react?
Noble gases have full subshells in their outermost shell, giving a very stable electronic arrangement. This makes it very difficult to remove an electron, so they rarely participate in chemical reactions.
What is the electron configuration of Ca²⁺, and which neutral atom has the same configuration?
Ca²⁺ has the configuration 1s² 2s² 2p⁶ 3s² 3p⁶.
This is identical to the configuration of argon.

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